The main function of a common power switch circuit is to send power supplied by a power supply to a load. At the moment that the load is enabled, an electrical conduction path between the load and the power supply must be formed in the power switch circuit so the load can receive the power from the power supply. During the operation of the load, if an abnormal condition (for example, an excessive current consumption is caused by the load, or an overcurrent is supplied from the power supply) occurs, the power switch circuit needs to form an open circuit immediately to protect the load and itself. Therefore, a reaction time of the power switch circuit is very important.